1. Field of the Invention
The present invention relates to a catheter for insertion into a body cavity. More particularly, it relates to a catheter for pristine isolation of a portion of a lung or transpharyngeal bronchial tube, and a method for use of the catheter.
2. Description of the Prior Art
Certain medical procedures require the insertion of a catheter into a body cavity for the purpose of examining a portion of the cavity, acquiring a pristine culture or biopsy of cells, introducing a fluid, or aspirating a fluid. Examples of such medical procedures include introducing a catheter into the urinary tract to determine and differentiate kidney infections from bladder or urethral infections, introducing a catheter into the uterus in post partum females to investigate sepsis of the uterus, and introducing a catheter into the tracheobronchial tree to investigate bronchial infections such a pneumonia. However, because the catheter must pass through an entry portion of the body cavity, for example the pharynx or vagina, prior to reaching the portion to be isolated or investigated, and because numerous micro-organisms different from those intended to be studied typically reside in those entry portions, the sterility of the catheter may be compromised and the sampling rendered valueless. Further, and infection may thereby be transmitted from one portion of the cavity to another due to the transit of the contaminated catheter.
When investigating the bronchial tree, a surgical technique known as Transtracheal Aspiration, in which an incision is made which bypasses the pharynx, has been developed in an effort to overcome this problem and attain uncontaminated lung or transpharyngeal bronchial samplings. However, Transtracheal Aspiration is often a dangerous procedure presenting the risks of cutaneous emphysema and hemoptysis, and, as a result, physicians are often hesitant to make use of it.
U.S. Pat. No. 4,023,559 to Gaskell is an example of a catheter designed to be inserted into a body cavity for sampling, irrigating, or draining a portion of the cavity while preventing the contamination of the sampling or drained portion by micro-organisms residing in entry portions of the cavity. The catheter there consists of an outer tube surrounding an inner tube and having a normally closed rounded distal end. The distal end has incisions which open under the pressure resulting from the axial movement of the inner tube. The inner tube remains retracted and the incisions closed as the catheter is passed into a body cavity so that the inner tube may remain sterile while the outer tube is thereby contaminated. When the distal end of the catheter reaches the desired portion of the body cavity, the still sterile inner tube is advanced through the incisions at the rounded distal end of the outer tube so that it may drain or introduce fluid. Optionally a sterile sampling means may be inserted through the lumen of the inner tube. The Gaskell catheter, however, has several shortcomings. First, since the outer tube walls must have sufficient resilient strength to firmly maintain the incisions in a closed condition during entry and exit, the outer tube must therefore be made of a relatively heavy guage tubing. This limits the catheter's flexibility. Secondly, because the outer edges of the incisions are contaminated with extraneous micro-organisms during the transit through the cavity, the previously sterile inner tube also becomes contaminated as it is extended through and contacts the incisions during use. The inner tube is, of course, again contaminated as it is withdrawn past the edges of the incisions after use. As a result, any sampling or culture taken will be contaminated by the inner tube and provide invalid results.